[openib-general] RFC: cma: need rdma_unbind

[Michael S. Tsirkin]

Sean, it seems that a rdma_unbind API is necessary for SDP SO_REUSEADDR support.
This should only remove association between the port and the id, without
affecting the CM state.

Reason: when SO_REUSEADDR is set, the port becomes usable immediately
after close call, but the QP must not be closed immediately -
rather its closed after graceful close or after timeout.

Thus I can not destroy the id, but the association with
port needs to be cancelled.

-- 
MST